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Primitive Bodies

The natural satellites of the giant planets of our Solar System are nearly all locked into resonances. There are spin-orbit resonances, resulting in synchronous rotations as for our Moon, but also orbital resonances between them. This configuration cannot be the result of a random process but is the consequence of slow dissipation acting over the ages, driving the system into a dynamical equilibrium.

Pity poor Mimas! The "that's no moon" moon of Saturn ought to be as famous as its sibling Enceladus. All other things being equal, Mimas should be more strongly tidally heated, but this is clearly not the case. This talk will review the latest Cassini findings for both moons, including the astonishing heat flow coming from Enceladus' south pole. It turns out that Mimas' lack of geologic activity is no surprise — the real question is how does Enceladus support its heat flow, active tectonics, and erupting plumes?

Dr. Showalter is a member of the Cassini Imaging Team and head of the PDS Rings node, which is housed at the SETI Institute. In this talk, Dr. Showalter will discuss the findings reported in his recent article in the journal Science.

The formation of the regular satellites of giant planets mirrors in profound ways the physical processes leading to the formation of the parent planetary bodies and provides an independent probe of the early history of the solar system. Ongoing results from the Cassini spacecraft are radically changing this field. Dr. Mosqueira will briefly describe combined Jupiter-Saturn models of satellite formation in disks of dust and gas, emphasizing exchange mechanisms taking place between the solar nebula and the subnebulae of the giant planets.

Dr Peter Jenniskens recently led a campaign in a NASA DC-8 aircraft to observe the reentry of the Japanese asteroid-hunting Hayabusa spacecraft in the Australian Outback. The international team collected awesome footage of the break-up of the spacecraft and the intact sample pod. Dr. Jenniskens will describe the organisation of the expedition and the first results of the observations.

The Stardust mission successfully returned samples from Comet Wild 2 in 2006. Studies of these samples have confirmed the presence of organics, some of which appear to be similar to those found in meteorites and some of which looks unlike anything seen in extraterrestrial materials before. The presence of D and 15N excesses in many of the organics suggests they have an interstellar chemical heritage. The nature of these organics, and their possible relationship to interstellar environments will be discussed.